Synthesis of (±)-5-epi-citreoviral and (±)-citreoviral and the kinetic resolution of an allylic silane by a [3+2] annulation

The [3 + 2] annulation reaction of allylsilane 1 with an alpha-keto ester provided the highly substituted tetrahydrofuran 2 as a single diastereomer in high yield. The synthesis of (+/-)-5-epi-citreoviral and (+/-)-citreoviral has been accomplished with this annulation reaction as the key step. Using the pantolactone-derived alpha-keto ester, the allylsilane 1 has been resolved with high enantiomeric purity.